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MERS is worrying – but not an emergency for now

By Debora MacKenzie

MERS, the novel Middle Eastern coronavirus that has so far killed 45 of the 84 people known to have caught it, is not a “public health emergency of international concern”, an emergency committee of the World Health Organization declared this week.

If MERS had been deemed an emergency, it would have alerted governments worldwide to brace for an impending new health threat.

The WHO says MERS is “serious and something that requires close monitoring”, but the committee’s decision suggests the WHO does not wish to be seen as overreacting to health threats, as it was accused of doing during the 2009 swine flu pandemic.

The committee spent the past week weighing the pros and cons of declaring an emergency now. The decision followed a four-hour teleconference involving an international team of health experts as well as representatives of countries where MERS infections have been diagnosed, including France, Germany, Italy, Jordan, Saudi Arabia, Qatar, Tunisia and the UK.

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Swine flu precedent

Only once before has a public health emergency of international concern been declared – for the 2009 swine flu pandemic. The WHO defines it as “an extraordinary event which… [could] potentially require a coordinated international response”.

Keiji Fukuda, head of health security at the WHO, said on Wednesday that this is “quite a dramatic action” which “can also have negative effects” – chiefly because “declarations and events have to be proportional to each other, otherwise you begin to lose credibility”.

The WHO was criticised for triggering worldwide emergency responses to the 2009 flu pandemic, which turned out to be relatively mild – although this could not be predicted at the outset. Now it appears to be caught in just such a dilemma.

Concern about MERS is high, said Fukuda&colon; with new cases reported almost daily, he says “this could really escalate and move beyond the region where it is right now”. Yet declaring 84 cases a global emergency is “probably not going to be seen as commensurate”.

Spreading freely?

Nonetheless there are fears that MERS could already be spreading freely among people in Saudi Arabia, instead of occasionally jumping to humans from its presumed animal host and then undergoing only limited human-to-human spread. On Wednesday, Saudi officials confirmed that two people who had been in contact with a MERS case, including a foreign health care worker, had developed the infection, although with mild symptoms. On Thursday, the WHO reported four new cases from the United Arab Emirates which were mild or without symptoms.

The discovery of more mild cases would suggest that the severe cases which have dominated the outbreak so far are merely the most obvious manifestations of an infection that is in fact much more widespread.

We have known since last year that MERS can occasionally spread among humans. The question now is whether MERS is in fact regularly spreading between people. If so, it could be adapting to humans and evolving to spread more readily.